Thursday, September 22, 2016

From the Raw

This project is completely made from raw material, no rough forgings, no parts "pirated" from elsewhere and no CNC, EDM or castings.  Every part, screw, pin and spring was, and will, be made here, by hand with the assistance of manual machinery.  It's going to be a rising bite, bar-in-wood, self opening, leverless, single trigger double rifle with inboard mounted sidelocks.  The caliber is 7.62x51R (that's .30-30 Winchester on this side of  the pond).  The false outer lockplates will have hinged, spring-loaded "access panels" (or maybe crystal windows) so that the lockwork can be seen.

The blank frame and the block of 1020 from which I cut it.
 
The barrel lump was machined from a piece of 4140 hexagonal bar.

The vertical bolt that works in unison with the underbolt, and makes it a rising bite action.

The frame after further machining.  The right-side fence is rough chiseled to shape.

The top strap TIG welded in place.

The barrels contoured and fitted to the lump, and the top strap joint is refined.  Also shown is the underbolt, vertical bolt, link and pivot as they are assembled in the frame.  It's clear how the axial travel of the underbolt translates to the rising bolt's vertical travel via the link.

The right-side inboard mounted sidelock. The outside "lockplate" is simply a cover and obviously will be pinless. I'm going to incorporate a spring-loaded trapdoor in the outer lockplates to access the inner workings.
The cocking lever is also the mainspring. As the barrels open, the lever/spring rotates the tumbler to full cock where the sear will hold it. As the barrels are closed, the cam at the front will cramp the spring.
This also makes it a self-opener.
The lockplate, the bridle and the screws are 1020 (they will be case-hardened), the tumbler, sear, sear spring, mainspring and cocking cam are made of O1 (an oil hardening steel).

To give some idea of the amount of work involved, here is a photo of the lock bridle after machining the posts but before shaping it by hand.

I decided that the bridles should be pierced, in the interest of saving weight (not really).

After some more thought, I decided that since the locks will be readily accessible (and therefore visible), that they should be more visually appealing.  To that end, I redesigned the sear spring (it's now a single-leaf with a bridge supporting it), beveled the edges of the bridle and bridge and cut an ornamental pattern into the lockplates (which had to be remade).

With the locks sorted, it's time to make the triggerplate.  Here's a shot of it early on.

Here is the triggerplate almost finished.  Now I have to decide on a single trigger or double triggers.
I had originally planned on a single trigger but double triggers on a side-by-side do have a certain aesthetic appeal.  I also decided against the sidelever, which I had considered, in favor of direct operation of the bolt via a slide in the forward portion of the triggerguard.  This is similar in concept to what is used in the Ljutic Mono trap gun.  It also allows the action to be completely symmetrical and ambidextrous.

Now it's time to work on the pattern stock.

I made a new, more functionally and aesthetically pleasing bolt slide and fabricated and welded the tang to the triggerguard.

 Next was to make the left and right firing pin bushings, firing pins, springs and vent screws.

 The blank for the forend iron with a portion of the bar of 1020 from which it was machined.

With the barrel breeches brazed, the barrels blacked down and the bolts fit, and the assembly proof-fired, I rewarded myself with some fun work.  That work is chiseling the fences.






No comments:

Post a Comment